The present invention relates to air/fuel mixers for internal combustion engines.
In U.S. Pat. No. 4,479,466 (the disclosure of which is incorporated herein by reference), there are disclosed air/fuel mixers for internal combustion engines, especially for engines of the type which use natural gas as a fuel. One disclosed embodiment therein involves a ring which has air inlet passages and which defines an internal volume to which air is introduced. A mixer body is provided which includes a truncated frusto-conical portion through which is formed a plurality of fuel passages. The fuel passages form outlets in a truncated frusto-conical surface of that portion, which surface is disposed within the internal volume of the ring. The air entering the internal volume under the influence of engine vacuum passes across the fuel outlets to draw fuel into the internal volume for being mixed with the air. A mixing chamber is formed at a truncated end of the truncated conical portion. Air and fuel passing across that chamber create a vacuum within the chamber which causes air and fuel to be drawn into the chamber for a more intensive mixing.
It has been found that such an arrangement operates satisfactorily for certain types of fuel, such as natural gas. However, for heavier fuels, such as diesel fuel, the incoming air may exhibit difficulty in drawing sufficient amounts of fuel through the fuel passages. Also, an incomplete mixing of the fuel and air may occur. Furthermore, the device is not as versatile as would be desired since separate devices must be designed for different engines in order to provide air inlet passages of proper size to admit an amount of air required by the particular engine.